Application of atomic data to quantitative analysis of tungsten - - PowerPoint PPT Presentation

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Technical Meeting on Uncertainty Assessment and Benchmark Experiments for Atomic and Molecular Data for Fusion Applications, 19-21 December 2016, Vienna, Austria

4/20

Application of atomic data to quantitative analysis of tungsten spectra on EAST tokamak

• L. Zhang1*, S. Morita2,3, X. D. Yang1, Z. Xu1, P. F. Zhang1, J. Huang1, T. Ohishi2,3, W. Gao1,
• Y. J. Chen1, X. J. Liu1, Z. W. Wu1, J. L. Chen1, L. Q. Hu1 and EAST team1

1 Institute of Plasma Physics Chinese Academy of Sciences, Hefei 230026, China 2 National Institute for Fusion Science, Toki 509-5292,Gifu, Japan 3 Department of Fusion Science, Graduate University for Advanced Studies, Toki 509-5292,Gifu, Japan

*E-mail: zhangling@ipp.ac.cn 19 Dec. 2016

ASIPP

Outline

• Background of W spectroscopy in EAST
• Upgrade of PFCs on EAST
• W spectroscopy in EAST
• W spectra measurement
• Hardware development (EUV spectrometers)
• Line analysis of W spectra at low/high T

e

• Space-resolved measurement of W spectra at high Te
• Quantitative analysis of W spectra
• In-situ absolute intensity calibration
• Methods for evaluation of W concentration
• Required atomic data
• W concentration in steady-state H-mode discharge
• Summary & Future work

ASIPP

Outline

• Background of W spectroscopy in EAST
• Upgrade of PFCs on EAST
• W spectroscopy in EAST
• W spectra measurement
• Hardware development (EUV spectrometers)
• Line analysis of W spectra at low/high T

e

• Space-resolved measurement of W spectra at high Te
• Quantitative analysis of W spectra
• In-situ absolute intensity calibration
• Methods for evaluation of W concentration
• Required atomic data
• W concentration in steady-state H-mode discharge
• Summary & Future work

ASIPP

2012

W Mo C

2014

FW: TZM (Titanium-Zirconium-Molybdenum) alloy Upper divertor: ITER-like W/Cu monoblock Lower divertor: SiC/C

• Wall conditioning;

Li coating, Si coating, B coating He-GDC, D2-GDC

• Gas puffing for diagnostics; Ar, He

Intrinsic & extrinsic impurities; He, Li, B, C, N, O, Si, Ar, Cr, Fe, Ni, Cu, Mo, W…

Upgrade of Plasma Facing Components on EAST

Mo C C

Monoblock

4/22

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W spectroscopy in EAST

• ITER has adopted tungsten as the divertor

material for the D-T operation.

• Impurity transport of tungsten in long pulse

discharges is a crucial issue for both the EAST and ITER. 5/22 W spectroscopy

ITER EAST

EAST

ASIPP

Outline

• Background of W spectroscopy in EAST
• Upgrade of PFCs on EAST
• W spectroscopy in EAST
• W spectra measurement
• Hardware development (EUV spectrometers)
• Line analysis of W spectra at low/high T

e

• Space-resolved measurement of W spectra at high Te
• Quantitative analysis of W spectra
• In-situ absolute intensity calibration
• Methods for evaluation of W concentration
• Required atomic data
• W concentration in steady-state H-mode discharge
• Summary & Future work

ASIPP

• Two EUV spectrometers at longer wavelength range (20-500Å);

EUV_Long: spectral measurement with fast response EUV_Long2: space-resolved measurement

− Slit width: 30μm/100μm (EUV_Long/EUV_Long2 with spatial resolution slit) − Varied line spacing groove concave holographic grating: 1200g/mm − Back-illuminated CCD (size: 26.6x6.6mm2, number of pixels: 1024x255)

− EUV_Long: 1024 (horizontal) spectral measurement, 255 (vertical) full binning − EUV_Long2: 255 (horizontal) spectral measurement, 1024 (vertical) space-resolved measurement

• One EUV spectrometer at shorter wavelength range (10-130Å)

EUV_Short: spectral measurement with fast response

− Slit width: 30μm − Varied line spacing groove concave holographic grating: 2400g/mm − Back-illuminated CCD (size: 26.6x6.6mm2, number of pixels:1024x255)

− 1024 (horizontal) spectral measurement − 255 (vertical) full binning

• Pulse motor for wavelength scan
• Laser light for optical alignment
• Turbo-molecular pump for vacuum system

7/22

Hardware development: EUV spectrometers (1) (Grazing incidence flat-field spectrometers)

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EUV_Short (viewing range is adjustable)

C port

EUV_Long EUV_Long2

EUV_Short

8/22

EUV_Long

D port

EUV_Long2 (viewing range is adjustable)

C port

Hardware development: EUV spectrometers (2) (Grazing incidence flat-field spectrometers)

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• 2nd order tungsten lines at 90-120Å can be easily

identified from UTA with high spectral resolution.

• Quantitative analysis of UTA is difficult.
• W spectra can not be generally observed in L-mode plasmas at low heating power.

The following W spectra are recorded after sudden drop of tungsten dust from upper divertor.

• T

e(0)=1.0keV, ne=3.5x1019m-3: USN, L-mode, PLHCD=0.5MW, Bt=2.25T, Ip=500kA, downward B

9/22

• Tungsten UTA (unresolved transition array) at 15-70Å is
• bserved by EUV_Short with high spectral resolution.
• UTA at 15-35Å can be compared with CoBIT data.

W24~28+ W28~33+ W24~28+ W28~32+

EUV_Short λ (Å) λ (Å) EUV_Long EUV_Long λ (Å) λ (Å)

transition 5f-4d 6g-4f 5p-4d 5g-4f

Line analysis of W spectra at low Te

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Line analysis of W spectra at higher Te

• W spectra are always observed with strong intensity in USN H-mode discharges. Additional 4.6GHz LHW and

ECRH heating increase the T

e higher than 2.5keV. Then, highly ionized W ions of W40+ to W45+ can be easily

measured with strong intensity. The following W spectra are recorded during ELM-free H-mode phase.

• T

e(0)=2.6keV, ne=3.7x1019m-3 : USN, PLHW/PICRH/PECRH=2.1/1.4/0.4MW, Bt=2.25T, Ip=450kA, downward B

W43+ (Ei=2.210keV) 4s24p 4p-4s (61.334, 126.29Å) W44+ (Ei=2.354keV) 4s2 4p-4s (60.93, 132.88Å) W45+ (Ei=2.414keV) 4s 4p-4s (62.336, 126.998Å)

• W40+ - W45+ lines with strong intensity are identified from the UTA.
• Weak isolated W42+ - W45+ lines at longer wavelength range are also

measured

10/22

W24~28+ W28~33+ W24~28+ W28~32+

EUV_Short EUV_Short λ (Å)

transition 5f-4d 6g-4f 5p-4d 5g-4f

EUV_Long EUV_Long λ (Å)

LiIII 135.0

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11/22

USN, PLHW2/PICRH/PECRH=2.2/0.6/0.3MW, steady-state ELMy H-mode

• The position of peak intensity for different

transition from the W ion with the same ionization stage is a little different, e.g. for W43+, W45+

• The profiles will be used to check the PEC

data

• With absolute intensity calibration and Abel

inversion, the tungsten density profile could be calculated Typical Te and ne profile

Space-resolved measurement of W spectra at high Te

ASIPP

Outline

• Background of W spectroscopy in EAST
• Upgrade of PFCs on EAST
• W spectroscopy in EAST
• W spectra measurement
• Hardware development (EUV spectrometers)
• Line analysis of W spectra at low/high T

e

• Space-resolved measurement of W spectra at high Te
• Quantitative analysis of W spectra
• In-situ absolute intensity calibration
• Methods for evaluation of W concentration
• Required atomic data
• W concentration in steady-state H-mode discharge
• Summary & Future work

ASIPP

In-situ absolute intensity calibration for EUV_Long

• Absolute intensity calibration of the EUV spectrometer is

necessary for the quantitative analysis of line emissions and bremsstrahlung continuum.

• Absolute intensity calibration at 20-150Å: comparison of

bremsstrahlung continua in EUV and visible ranges.

• Relative intensity calibration at 130-300Å: line pairs of 2p-

2s/3p-3s transitions of Li and Na-like ions from EAST.

Candidate line pairs in EAST plasma:

13/22

EUV spectra have to be checked before the calibration whether the metallic impurity is negligible or not because of its large recombination rate. There is a wavelength gap between Cr XXII and Ar XVI.

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Method for evaluation of W concentration (1): using chord-integrated tungsten line intensity

• Evaluation of cW from chord-integrated line

intensity, e.g. IW44+-IW45+

• W concentration, or

IWq+ : measured chord-integrated line intensity from Wq+ nWq+ : density of Wq+ PECWq+ : photon emissivity coefficient of line from Wq+ ne : electron density cW (r): density profile of W, fCw : normalized density profile of W FAWq+ : fractional abundance of Wq+ under ionization equilibrium

14/22

• T. Nakano et al., J. Phys. B 48 (2015) 144023

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• The cw is analyzed for a target shot.
• Calibration shot with similar T

e profile to the

target shot is required; a sudden increase in the radiation power loss caused by cw increase.

• Radiation power loss is measured by

bolometer system.

• Cooling rate (Radiation power coefficient):
• Radiation power loss by W:
• For calibration shot:

cW (r): density profile of W, fCw(r) : normalized density profile of W IW-UTA: chord-integrated intensity of W-UTA at 45-70Å

• For target shot:

15/22 calibration shot

Method for evaluation of W concentration (2): using radiation power loss

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Method for evaluation of W concentration (3): using space-resolved tungsten line intensity

• Density profile of W ions nwq+(r), e.g. for W42+-W45+,

can be obtained from the space-resolved measurement of impurity line intensity.

• Chord-integrated line intensity, e.g. IW42+-IW45+
• Multi-channel IWq+ (e.g. 64 channels for EUV_Long2)

IWq+ : measured chord-integrated line intensity from Wq+ εwq+: emissivity of line from Wq+ nWq+ : density of Wq+ PECWq+ : photon emissivity coefficient of line from Wq+

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EFIT Abel Inversion

nwq+(r) εwq+(r) T

e(r), ne (r), PEC(T e,ne)

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• ADAS-IC: with J-resolved fine structure energy levels (arf40_ic series)
• ADAS-LS: with J-unresolved LS levels (arf40_ls series)

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Atomic data (1): PEC (photon emissivity coef.) of W lines

λ (Å) √ √ √ λ (Å) √ √ √ x x

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• Data from open-ADAS are used in the set of

rate equations.

• Effective ionization coefficient (scd50_w.dat)
• Effective recombination coefficient (acd50_w.dat)
• Effect of impurity transport should be

considered.

Atomic data (2): Fractional Abundance of Wq+ ions

18/22

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LHD experiment & CR model (line emission) Original ADPAK model: average ion model Sasaki and Murakami model Pütterich calculation Estimation from bolometer measurement

I Murakami et al., Nucl. Fusion 55(2015) 093016 D Post et al., At. Data Nucl. Data Tables 20(1977) 397 Open-ADAS T Pütterich et al., Nucl. Fusion 50(2010) 025021

Atomic data (3): Tungsten cooling rate

19/22

Pütterich 2010

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Method nW(0)/ne(0) NW/Ne PEC W42+ 129.41Å 1.1x10-3 3.9x10-4 W43+ 61.334Å 4.5x10-5 1.6x10-5 W43+ 126.29Å 6.3x10-5 2.3x10-5 W44+ 60.93Å 1.6x10-5 5.6x10-6 W45+ 62.336Å 1.9x10-5 6.7x10-6 W45+ 126.998Å 2.4x10-5 8.8x10-6 Cooling rate AIM 4.3x10-5 1.5x10-5 Pütterich 5.3x10-5 1.9x10-5 ADAS 9.1x10-5 3.2x10-5

20/22

W concentration in steady-state ELMy H-mode

• The evaluated Cw from W42+ is one order of

magnitude higher than that from other lines

• The evaluated Cw is in the range of 5x10-6-

3x10-5 USN, PLHW1/PLHW2/PECRH=0.4/2.2/0.3MW

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Summary & Future work Summary

• Tungsten spectra have been measured in EAST discharges using newly installed EUV
• spectrometers. Line analysis of tungsten spectra has been done.
• Two Methods for evaluation of tungsten concentration based on the cooling rate of

tungsten ions and the PEC of W42+ - W45+ ions are introduced with the required atomic data.

• The Cw in steady-state H-mode discharge with RF heating is evaluated to be in a range of

5x10-6 - 3x10-5 with different methods, while the evaluated Cw from W42+ is one order of magnitude larger than that from other lines.

• Vertical profiles of chord-integrated tungsten line intensity have been measured in steady-

state H-mode discharges. Further analysis is being now progressed.

Future work

• To measure and identify the emission lines of W ions in longer wavelength range.
• To make closer collaboration on the tungsten study with atomic physicists.
• To study the tungsten transport with combination of quantitative measurement and

simulation. 21/22

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THANK YOU FOR YOUR ATTENTION